Relaxation length with FIALA model

Luca Cavagna_21621
Luca Cavagna_21621 Altair Community Member
edited August 2023 in Community Q&A

Hello

I am using the classic fiala model for landing gear modelling.

I saw the example fiala_195_55_R16.tir in the Altair folder and I see the rlenx is a very very small value.

I tried to use a value I gussed from NASA-TR-T64 model which for my tire is approx 25inches. When I use this value I get a very weird response (I would say not phisical).

Are we sure the rlenx must be input with some sort of scaling? The example indicated 0.242 mm ???

Thanks

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Answers

  • Jagadeesh R
    Jagadeesh R
    Altair Employee
    edited August 2023

    hI Luca Cavagna,

    Please use Other tire property files from the installation file (except fiala_195_55_R16.tir, its just a sample file), which have more parameters to represent the tire model. You can take "fiala_point_contact_car205_60_R15.tpf" (below marked), and check for the required input values. For more information about Fiala point and cam contact, refer in help document.

    image

    thanks,

    jagadeesh

     

  • Luca Cavagna_21621
    Luca Cavagna_21621 Altair Community Member
    edited August 2023

    Hello jagadeesh

    thanks for the reply. I saw those examples. Thanks for pointing me there.

    For the moment I am doing my calcs with a relax. lenght as low as possibile to avoid numeric instabilities. That implies a static response for the tire and for the moment at a conceptual design stage it's ok.

    Anyhow, there's a dependence on the CSLIP and the relax. lenght and the CSLIP depends on the vertical load and tire deflection. That value therefore changes but we have just one input value. It would be nice to be able to provide a table of CSLIP with Fz (ADAMS enhanced tire can).

    Again, thanks a lot for your help.

    Cheers

     

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